Significant improvement to HIV counseling and testing (HCT), linkage and care are critical to turn the tide of the HIV epidemic. The first step i reaching universal access to HIV prevention and treatment is to significantly increase uptake of annual HIV testing among all South African adults. Expanding HIV testing and referral strategies to include self-testing through social/sexual networks may improve early detection, particularly among hard-to-reach populations with undiagnosed cases of HIV infection. In this study, we propose to address three key areas identified in RFA-AI-14-009: HIV prevention in young women, combination prevention strategies, and identification of infected individuals and linkage to care by exploring how self-testing for HIV may improve testing coverage and frequency among young women and their peers and partners, thus decreasing the burden of undiagnosed infections and improving entry into care. We propose randomizing 400 young women in the Agincourt Health and Socio-demographic Surveillance Site in rural Mpumalanga Province, to receipt of clinic-based HCT or to choice of either HCT or HIV self-testing. Young women in both arms will be encouraged to invite 2 friends and up to 2 partners to test for HIV using the strategy they are assigned or have chosen, leading to referral of up to 1600 friends/partners for testing. Young women and consenting peers/partners will be followed to assess study outcomes both quantitatively and qualitatively. Outcomes to be explored include testing uptake, testing referral, frequency of testing, diagnosis of new positives, and linkage to care. The Agincourt research platform is purpose-designed to achieve high follow-up and cohort integrity. Outcomes will be compared by study arm. Those who test positive will be counseled and encouraged to link to care, including receipt of text messages to promote linkage and actively linking those who fail to present for CD4 test results within 3 months. This will be among the first studies to measure the uptake of self-testing among young women in sub-Saharan Africa, a group at extremely high risk, and will elucidate how expanded testing choices can impact testing uptake for young women, their peers and partners. To date it is unknown whether young people will take up self-testing, whether self-testing can improve testing frequency, whether referral of friends and partners will result in greater testing uptake and identification of undiagnosed infections, and whether those that self-test will link to care. Our work will inform scale up of expanded HIV testing and linkage to care in South Africa. The proposed intervention, if found efficacious, will provide public health tools that increase HIV testing and linkage to care among a population disproportionately affected by HIV - a key objective in Government's 2012-16 National Strategic Plan.